Ultrasound is a non-invasive, safe, low cost and practical way to provide medical doctors with an internal view of a patient's body. By reconstructing a 3D volume from hundreds of ultrasound scans, physicians can see the internals of the body in ways otherwise impossible from scans alone. There are different ways to reconstruct the volume, and these differ in the reconstruction quality and speed. There are also different ways to visualize the resulting volume. This chapter describes how ultrasound is used in medicine and introduces different methods of reconstruction and visualization. Previous work in the field of ultrasound reconstruction and visualization is also presented.